Vaping’s effects still uncertain

Mon., March 21, 2016

Re: Pot-vaping rules still need tweaking, Letter March 16

Pot-vaping rules still need tweaking, Letter March 16

Dr. Vincent Maida objects to the Ontario government’s latest proposal to regulate medicinal marijuana use in enclosed public places, which he views as unacceptable interference in patients’ rights to take prescribed pain medication. It’s a laudable and valid concern, yet it’s also important to preserve the rights of others to control what they inhale.

I applaud the currently modified policy especially for its limitations on public marijuana smoking (i.e., combustion products). Many patients’ rights arguments about vapour have also been made about smoke, but emerging evidence suggests second-hand marijuana smoke has the same or worse effects on blood vessels as second-hand tobacco smoke. Therefore, the patients’ rights argument is insufficient to justify compelling the public to cede control over what they inhale indoors.

I agree with his basic premise that it is unacceptable to interfere with patients’ use of a necessary medicine. However, the statement needs to be qualified, as it is also unacceptable to force non-patients to take that same medicine in the process (or to be exposed to other ingredients in the formulation). Leaf vapourizer emissions do not contain combustion products, but it is still unknown what is emitted along with the cannabinoids and what effects they may have, especially on bystanders who have other medical conditions that might be adversely affected by components of the vapour.

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I won’t challenge Dr. Maida’s assertion that the cannabinoid level in this vapour is extremely minute. However, at least in the U.S., many people with medical marijuana prescriptions don’t suffer from medical conditions. If people are enticed to get illegitimate prescriptions for the ability to vapourize marijuana in movie theatres, it could easily result in half the audience (depending on the movie) puffing away and producing far higher levels of vapourization products than what is expected from a single device.

There are ways to take cannabinoids that don’t impact air quality and expose bystanders (witness the surging medicinal “edibles” industry).

Until we have a better understanding of marijuana leaf vapourization emissions, it is sensible and scientifically valid to limit their use in enclosed public spaces.

Dr. Matthew L. Springer, professor of medicine, University of California, San Francisco